1. Field of the Invention
The present invention relates to organic photosensitive optoelectronic devices, and more particularly to an organic light detector capable of suppressing dark current.
2. Description of Related Art
Optoelectronic devices such as LEDs, solar cells and light detectors produce electromagnetic radiation or electrical current by using optical or electrical properties of materials forming the devices.
For example, a light detector utilizes a photosensitive element to convert an optical signal into an electrical signal. Generally, the photosensitive element detects light of a wavelength near the visible spectrum. In particular, after the photosensitive material of the photosensitive element absorbs electromagnetic radiation, it produces an excited molecular state, i.e., an exciton with an electron-hole pair. When the electron-hole pair is separated, a photocurrent is produced. To speed up the absorption of carriers by the anode and cathode, a reverse bias is usually applied, which however causes injection of carriers from the anode or cathode to be reversely injected into the photosensitive material, thus resulting in inaccuracy of the current value measured by the detector.
WO2007/017475 discloses an organic light detector with an electron blocking layer for blocking dark current produced by injection of electrons from an anode to an active layer. However, since in the prior art only the electron blocking layer are used to block the electrons injected from the anode to the active layer, the low work function metal electrodes are utilized which are usually unstable, thereby reducing the lifetime of the device.
Therefore, there is a need to provide an organic photosensitive optoelectronic device capable of reducing dark current and providing options of metal electrodes of more stable materials so as to enhance sensitivity and lifetime of the optoelectronic device and to overcome the above drawbacks.